As dominant as the All Blacks have been in 2013 - and you simply do not get any better than 14-0 - it's hard to shake a feeling that the chasing pack are closing the gap behind them. It just may be that their record flatters them.

If there's an abiding memory from this last month on the hoof around the planet, it's that for a team chasing - and achieving - a form of perfection, and for a group that likes to scribble lofty, ethereal goals on their whiteboard, the All Blacks have appeared strangely vulnerable. For a bunch of supermen - as they're often portrayed up here - their mortality has never seemed more vivid.

The last three weekends of their season surely reinforced that. France, England and most recently those firebrand Irish have all given the All Black tree a fairly hefty shake.

They haven't just been competitive, but all three have shown the ability to live with the world's best team, as well as to unsettle them with their direct, physical play.

On the surface it should be a pretty pleasant summer for Steve Hansen as he spends some well deserved downtime with his fiance, family and friends. He's ticked a lot of boxes in 2013 and he's guided the team to uncharted territory, which is no mean feat for an All Black coach.

Not since the game turned professional, and schedules became entrenched, have the All Blacks won every test in a year. That alone suggests Hansen is about as on target as he can be a season and a-half out from a World Cup mission that will define his 12-year association with this team.

But, those of us who have been living and breathing these guys for the last month, or more, have also sensed a little bit of a flattening of the line.

Maybe that's just the toll of a long and demanding season, and a pretty fierce challenge from the South Africans in the Rugby Championship. Maybe.

But then you look at France, and then England, and then Ireland, and you think that one might be a fluke, but two and then three is definitely a trend.

The All Blacks are still good enough to beat these guys in their own backyards - and that should never be taken for granted - but gee it's suddenly got mighty difficult.

If the All Blacks take that information and feed it into the giant computer that powers them, they'll be better for it.

They need to acknowledge that the northern challenge is no longer nominal, and no longer a myth. It's pretty deep-seated, and it's pretty real.

But, of course, the All Blacks remain the standard that everyone is aspiring to. And there's no reason to think that they won't get better over the next couple of years, and retain that competitive advantage they have over their pursuers.

Though there is a fairly entrenched senior core in this group, there's also a pretty exciting swathe of youngsters making their mark, or looking like they might soon.

Charles Piutau has been the find of the season., and if Hansen and his colleagues are smart they may look at him, not Ben Smith, as the solution to their midfield backup problems.

Steven Luatua will also be something special sooner rather than later. Sam Cane is well on the way to becoming a brilliant No 7.

Who knows how quickly Ardie Savea will catch him up. In Aaron Cruden and Beauden Barrett - a young man with uncanny impact ability - the depth is crazy good at No 10.

You forget Brodie Retallick is still only 22, and that Sam Whitelock - already past a half-century of caps - is just 25. Dane Coles has incredible upside and is just scratching the surface of the hooker position, and Julian Savea - who came of age on this tour - is only 23. He's adding stratas to his game with every outing.

The telling thing is that they have men like Kieran Read, Richie McCaw, Liam Messam and Conrad Smith as their role models. Men who don't just play like All Blacks, but live like them too.

Hansen is sure the experiences of this tour, the dark places the team had to go simply to win tests, is a bankable commodity. Especially among his greenhorns.

"What we'll take out of this [tour] is our coaching group and our young players who haven't been in this situation with the All Blacks before will realise it doesn't matter what the scoreboard says, it's about doing what you have to do in that moment, at that time, and if you do that and you've got the talent and the mental fortitude and the composure, then you're still a chance.

"You're not always going to get there, but you're still a chance. This will be massively good for our young players to now realise they've been through that."

If anything the last month has taught the All Blacks their most valuable lesson of 2013. As good as they are - and they are the best in the business - the other big dogs are most certainly nipping at their heels.

WHAT THE TOUR TOLD US

THE DIFFERENCE MAKERS

Kieran Read: The best player in the game. Big ticker, big skills and big game.

Ben Smith: Not a centre. But a fabulous footballer who makes a difference.

Julian Savea: Now the pre-eminent wing in world rugby. Has figured a lot out.

THOSE WHO GRABBED THEIR CHANCE

Charles Piutau: Arguably the find of the tour. This kid looks born to play test footy.

Aaron Cruden: Time and again he's answered the call. If he could only run a game like Dan.

Steven Luatua: Solid tour, but you just know this kid is building to something very special.

THOSE TREADING WATER

Owen Franks: Been a tough year. Let's see how he bounces back in 2014.

Aaron Smith: Not the commanding figure of 2012. Has a bit to think about.

Ma'a Nonu: Good. Very good. But not the dominant figure he can be.

THOSE SLIPPING BACKWARDS

Cory Jane: Only had two tests. But has a lot to do after a flat last effort.

Dan Carter: Still a class act, if only his body would play ball.

Andrew Hore: Is this the end of the venerable No 2? Probably time to move on.